Methods and systems to form propylene chlorohydrin and propylene oxide

ABSTRACT

There are provided methods and systems to form propylene chlorohydrin by hydrolysis of 1,2-dichloropropane and to further form propylene oxide from propylene chlorohydrin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No. 62/512,900, filed May 31, 2017; U.S. Provisional Application No. 62/531,669, filed Jul. 12, 2017; and U.S. Provisional Application No. 62/596,215, filed Dec. 8, 2017, all of which are incorporated herein by reference in their entirety in the present disclosure.

BACKGROUND

Polyurethane production remains one of the environmentally challenging manufacturing processes in industrial polymerization. Formed from addition reactions of di-isocyanates and polyols, polyurethanes may have a significant embedded environmental footprint because of the challenges associated with both feedstocks. Polyols are themselves polymerization derivatives which use propylene oxide as raw materials. Traditionally, propylene oxide (PO) may be synthesized from a chlorinated intermediate, propylene chlorohydrin. However, an environmentally acceptable process for the economic production of propylene oxide remains elusive. High costs of chlorine and significant waste water production (approximately 40 tonnes of waste water per tonne of PO) has caused manufacturers to look for process options with reduced environmental and safety risks.

SUMMARY

Provided herein are environmentally friendly methods and systems to produce propylene chlorohydrin (PCH) and propylene oxide (PO) in high yields and high selectivity with significantly less side products and/or waste materials.

In one aspect, there are provided methods to form PCH, comprising:

(i) contacting an anode with an anode electrolyte in an electrochemical cell wherein the anode electrolyte comprises metal chloride and saltwater; contacting a cathode with a cathode electrolyte in the electrochemical cell; applying voltage to the anode and the cathode and oxidizing the metal chloride with metal ion in a lower oxidation state to a higher oxidation state at the anode;

(ii) withdrawing the anode electrolyte from the electrochemical cell and chlorinating propylene with the anode electrolyte comprising metal chloride with metal ion in higher oxidation state and the saltwater to result in one or more products comprising PCH and dichloropropane (DCP), and the metal chloride with the metal ion in lower oxidation state;

(iii) separating the one or more products comprising PCH and DCP from aqueous medium; and

(iv) hydrolyzing the DCP with water to form the PCH.

In one aspect, there are provided methods to form PCH, comprising:

(i) oxidizing metal chloride with metal ion in a lower oxidation state to a higher oxidation state in presence of an oxidant in an oxychlorination reaction;

(ii) withdrawing the metal chloride with metal ion in the higher oxidation state from the oxychlorination reaction and chlorinating propylene with the metal chloride with the metal ion in the higher oxidation state in saltwater under reaction conditions to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state;

(iii) separating the one or more products comprising PCH and DCP from aqueous medium; and

(iv) hydrolyzing the DCP with water to form the PCH.

In one aspect, there are provided methods to form PCH, comprising:

(i) contacting an anode with an anode electrolyte in an electrochemical cell wherein the anode electrolyte comprises metal chloride and saltwater; contacting a cathode with a cathode electrolyte in the electrochemical cell; applying voltage to the anode and the cathode and oxidizing the metal chloride with metal ion in a lower oxidation state to a higher oxidation state at the anode;

(ii) withdrawing the anode electrolyte from the electrochemical cell and chlorinating propylene with the anode electrolyte comprising metal chloride with metal ion in higher oxidation state and the saltwater to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state;

(iii) extracting the one or more products comprising PCH and DCP from aqueous medium by extracting with DCP as an extraction solvent; and

(iv) hydrolyzing the DCP with water to form the PCH.

In one aspect, there are provided methods to form PCH, comprising:

(i) oxidizing metal chloride with metal ion in a lower oxidation state to a higher oxidation state in presence of an oxidant in an oxychlorination reaction;

(ii) withdrawing the metal chloride with metal ion in the higher oxidation state from the oxychlorination reaction and chlorinating propylene with the metal chloride with the metal ion in the higher oxidation state in saltwater under reaction conditions to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state;

(iii) extracting the one or more products comprising PCH and DCP from aqueous medium by extracting with DCP as an extraction solvent; and

(iv) hydrolyzing the DCP with water to form the PCH.

In some embodiments of the foregoing aspect, the DCP as the extraction solvent is the DCP separated and recirculated from the same process and/or is DCP from other sources.

In some embodiments of the foregoing aspects and embodiment, the amount of the DCP in the hydrolysis is between about 10-95% by volume.

In some embodiments of the foregoing aspects and embodiments, the hydrolysis is catalyzed by presence of a nobel metal selected from ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold, mercury, rhenium, titanium, niobium, tantalum, and combinations thereof.

In some embodiments of the foregoing aspects and embodiments, the hydrolysis is carried out in presence of metal hydroxychloride species of stoichiometry M_(x) ^(n+)Cl_(y)(OH)_((nx-y)), such as, for example only, Cu_(x)Cl_(y)(OH)_((2x-y)).

In some embodiments of the foregoing aspects and embodiments, the method further comprises after extraction, transferring aqueous medium comprising the metal chloride with metal ions in the higher oxidation state and the lower oxidation state to the oxychlorination reaction and oxidizing the metal ion of the metal chloride from the lower oxidation state to the higher oxidation state in presence of the oxidant. In some embodiments of the foregoing aspects and embodiments, the oxidant is HCl and oxygen or hydrogen peroxide (or any other oxidant as described herein). In some embodiments of the foregoing aspects and embodiments, the method further comprises forming HCl by the hydrolysis of the DCP to the PCH; separating the HCl; and transferring the HCl to the oxychlorination reaction; and/or adding other HCl to the oxychlorination reaction. The “other HCl” has been described herein. In some embodiments of the foregoing aspects and embodiments, the method further comprises recirculating the metal chloride with the metal ion in the higher oxidation state back to the chlorination reaction and/or the electrochemical reaction.

In some embodiments of the foregoing aspects and embodiments, the method further comprises after extraction, transferring aqueous medium comprising the metal chloride with metal ion in the higher oxidation state and the lower oxidation state to the hydrolysis reaction.

In some embodiments of the foregoing aspects and embodiments, the PCH is formed with selectivity of between about 20-100% by wt and/or more than 0.01 STY.

In some embodiments of the foregoing aspects and embodiments, the method further comprises after hydrolysis, transferring organic medium comprising PCH and DCP to epoxidation; and epoxidizing the PCH with a base to form PO in presence of the DCP. In some embodiments of the foregoing aspects and embodiments, the base is selected from alkali metal hydroxide, alkali metal oxide, alkaline earth metal hydroxide, or alkaline earth metal oxide. In some embodiments of the foregoing aspects and embodiments, the base is a metal hydroxychloride species, such as copper hydroxychloride species of stoichiometry Cu_(x)Cl_(y)(OH)_((2x-y)). In some embodiments of the foregoing aspects and embodiments, metal in the metal hydroxychloride is same as metal in the metal chloride. In some embodiments of the foregoing aspects and embodiments, the method further comprises forming the metal hydroxychloride by oxychlorinating the metal chloride with the metal ion in the lower oxidation state to the higher oxidation state in presence of water and oxygen. In some embodiments of the foregoing aspects and embodiments, the base is between about 5-38 wt %.

In some embodiments of the foregoing aspects and embodiments, the reaction forms between about 5-42 or 5-40 tonnes of brine per tonne of PO.

In some embodiments of the foregoing aspects and embodiments, the saltwater comprises alkali metal chloride or alkaline earth metal chloride.

In some embodiments of the foregoing aspects and embodiments, metal ion in the metal chloride is selected from the group consisting of iron, chromium, copper, tin, silver, cobalt, uranium, lead, mercury, vanadium, bismuth, titanium, ruthenium, osmium, europium, zinc, cadmium, gold, nickel, palladium, platinum, rhodium, iridium, manganese, technetium, rhenium, molybdenum, tungsten, niobium, tantalum, zirconium, hafnium, and combination thereof.

In some embodiments of the foregoing aspects and embodiments, the metal chloride is copper chloride.

In some embodiments of the foregoing aspects and embodiments, the method further comprises adding other DCP to the chlorination; to the hydrolysis; and/or to the epoxidation for the extraction. In some embodiments of the foregoing aspects and embodiments, the other DCP is obtained from a traditional chlorohydrin process and/or from direct chlorination of propylene with chlorine.

In some embodiments of the foregoing aspects and embodiments, the one or more products further comprise isopropanol and/or isopropyl chloride. In some embodiments of the foregoing aspects and embodiments, the method further comprises converting the isopropanol and/or the isopropyl chloride back to the propylene, DCP, and/or PCH.

In one aspect, there are provided systems to form PO, comprising:

(i) an electrochemical cell comprising an anode chamber comprising an anode and an anode electrolyte wherein the anode electrolyte comprises metal chloride and saltwater and the anode is configured to oxidize the metal chloride with metal ion in a lower oxidation state to a higher oxidation state; a cathode chamber comprising a cathode and a cathode electrolyte; and a voltage source configured to apply voltage to the anode and the cathode;

(ii) a chlorination reactor operably connected to the anode chamber of the electrochemical cell and configured to obtain the anode electrolyte and chlorinate propylene with the anode electrolyte comprising the metal chloride with the metal ion in the higher oxidation state in the saltwater to result in one or more products comprising DCP and the metal chloride with the metal ion in the lower oxidation state;

(iii) a hydrolysis reactor operably connected to the chlorination reactor and configured to obtain the one or more products comprising DCP from the chlorination reactor with or without the saltwater comprising metal chloride and configured to hydrolyze the DCP to PCH; and

(iv) an epoxidation reactor operably connected to the hydrolysis reactor and configured to obtain the solution comprising DCP and PCH and epoxidize the PCH to PO in presence of a base.

In one aspect, there are provided systems to form PO, comprising:

(i) an oxychlorination reactor configured to oxidize metal chloride with metal ion in lower oxidation state to higher oxidation state using an oxidant (oxidants have been described herein);

(ii) a chlorination reactor operably connected to the oxychlorination reactor and configured to obtain the metal chloride with the metal ion in the higher oxidation state and chlorinate propylene with the metal chloride with the metal ion in the higher oxidation state in the saltwater to result in one or more products comprising DCP and the metal chloride with the metal ion in the lower oxidation state;

(iii) a hydrolysis reactor operably connected to the chlorination reactor and configured to obtain the one or more products comprising DCP from the chlorination reactor with or without the saltwater comprising metal chloride and configured to hydrolyze the DCP to PCH; and

(iv) an epoxidation reactor operably connected to the hydrolysis reactor and configured to obtain the solution comprising DCP and PCH and epoxidize the PCH to PO in presence of a base.

In one aspect, there are provided systems to form PO, comprising:

(i) a chlorination reactor configured to chlorinate propylene with chlorine to result in one or more products comprising DCP;

(ii) a hydrolysis reactor operably connected to the chlorination reactor and configured to obtain the one or more products comprising DCP from the chlorination reactor and configured to hydrolyze the DCP to PCH; and

(iii) an epoxidation reactor operably connected to the hydrolysis reactor and configured to obtain the solution comprising DCP and PCH and epoxidize the PCH to PO in presence of a base.

In some embodiments of the foregoing aspects and embodiments, the system further comprises an oxychlorination reactor

operably connected to the chlorination reactor and/or the electrochemical cell;

operably connected to the hydrolysis reactor; and

configured to obtain aqueous medium from the chlorination reactor and/or the electrochemical cell comprising the metal chloride with metal ion in the lower oxidation state and the higher oxidation state;

configured to obtain HCl produced in the hydrolysis reactor; and

configured to oxidize the metal chloride with metal ion in the lower oxidation state to the higher oxidation state using an oxidant comprising the HCl and oxygen, or hydrogen peroxide (or any other oxidant known in the art).

In some embodiments of the foregoing aspect and embodiments, the system further comprises the chlorination reactor and/or the hydrolysis reactor operably connected to a traditional chlorohydrin system and/or to another chlorination reactor chlorinating propylene with chlorine, and configured to obtain other DCP from the traditional chlorohydrin system and/or from the another chlorination reactor chlorinating propylene with chlorine.

In one aspect, there is provided a method to form propylene chlorohydrin (PCH), comprising: chlorinating propylene in an aqueous medium comprising metal chloride with metal ion in higher oxidation state and salt to result in one or more products comprising propylene chlorohydrin (PCH), and the metal chloride with the metal ion in lower oxidation state. In some embodiments of the foregoing aspect, the one or more products further comprise 1,2-dichloropropane (DCP). In some embodiments of the foregoing aspect and embodiment, the method further comprises separating DCP from the aqueous medium and converting the DCP to the PCH. In some embodiments of the foregoing aspect and embodiment, the method further comprises hydrolyzing the DCP to the PCH in situ.

In some embodiments of the foregoing aspect and embodiments, the method further comprises adding platinum or palladium to the aqueous medium to form PCH in yield of between about 10-100%. In some embodiments of the foregoing aspect and embodiments, the platinum or palladium is in concentration of between about 0.001-0.1M.

In some embodiments of the foregoing aspect and embodiments, the method further comprises chlorinating propylene in presence of oxygen.

In some embodiments of the foregoing aspect and embodiments, reaction conditions for the chlorination reaction comprise temperature between 20-150° C., pressure between 125-350 psig, or combination thereof.

In some embodiments of the foregoing aspect and embodiments, the one or more products further comprise isopropanol and/or isopropyl chloride. In some embodiments of the foregoing aspect and embodiment, the method further comprises converting the isopropanol and/or the isopropyl chloride back to the propylene.

In some embodiments of the foregoing aspect and embodiments, the one or more products further comprise hydrochloric acid (HCl). In some embodiments of the foregoing aspect and embodiment, the method further comprises after the chlorinating step, oxychlorinating the metal chloride with the metal ion in the lower oxidation state to the metal ion in the higher oxidation state in presence of the HCl and oxygen.

In some embodiments of the foregoing aspect and embodiment, the method further comprises recirculating the metal chloride in the higher oxidation state back to the chlorinating step.

In some embodiments of the foregoing aspect and embodiment, the method further comprises reacting the PCH with a base to form propylene oxide (PO). In some embodiments of the foregoing aspect and embodiments, the base is an alkali metal or alkaline earth metal hydroxide. In some embodiments of the foregoing aspect and embodiments, the base is metal hydroxychloride. In some embodiments of the foregoing aspect and embodiments, metal in the metal hydroxychloride is same as metal in the metal chloride. In some embodiments of the foregoing aspect and embodiment, the method further comprises forming the metal hydroxychloride by oxychlorinating the metal chloride with the metal ion in the lower oxidation state to the higher oxidation state in presence of water and oxygen.

In some embodiments of the foregoing aspect and embodiments, the reaction further forms brine in water. In some embodiments of the foregoing aspect and embodiments, the reaction forms between about 5-45 or 5-42 tonnes of brine per tonne of PO.

In one aspect, there is provided a method to form propylene oxide (PO), comprising chlorinating propylene in an aqueous medium comprising metal chloride with metal ion in higher oxidation state and salt to result in one or more products comprising between about 5-99.9 wt % propylene chlorohydrin (PCH), and the metal chloride with the metal ion in lower oxidation state; and reacting the PCH with a base to form propylene oxide (PO) and brine in water, wherein the reaction forms between about 5-45 or 5-42 or 5-40 tonnes of brine per tonne of PO. In some embodiments of the foregoing aspect, the base is between about 5-38 wt % or between about 5-35 wt % or between about 8-15 wt % sodium hydroxide or calcium hydroxide or calcium oxide (or any other base as described herein).

In some embodiments of the foregoing aspects and embodiment, the method further comprises transferring the aqueous medium comprising the metal chloride with the metal ion in the lower oxidation state and the salt to an anode electrolyte in contact with an anode in an electrochemical cell and oxidizing the metal ion from the lower oxidation state to the higher oxidation state at the anode.

In some embodiments of the foregoing aspects and embodiment, the method further comprises transferring the aqueous medium comprising the metal chloride with the metal ion in the lower oxidation state and the salt to an oxychlorination reaction and oxidizing the metal ion from the lower oxidation state to the higher oxidation state in the presence of HCl and oxygen.

In some embodiments of the foregoing aspects and embodiments, the salt comprises alkali metal chloride or alkaline earth metal chloride.

In some embodiments of the foregoing aspects and embodiments, total amount of chloride content in the aqueous medium is between 3-15M or between 3-5M or between 3-4M.

In some embodiments of the foregoing aspects and embodiments, salt comprises sodium chloride, and the metal chloride in the higher oxidation state is in range of 0.1-8M or between about 0.1-3 or between about 0.1-2.5M, the metal chloride in the lower oxidation state is in range of 0.1-2M and the sodium chloride is in range of 0.1-5M or between about 0.1-3M.

In some embodiments of the foregoing aspects and embodiments, metal ion in the metal chloride is selected from the group consisting of iron, chromium, copper, tin, silver, cobalt, uranium, lead, mercury, vanadium, bismuth, titanium, ruthenium, osmium, europium, zinc, cadmium, gold, nickel, palladium, platinum, rhodium, iridium, manganese, technetium, rhenium, molybdenum, tungsten, niobium, tantalum, zirconium, hafnium, and combination thereof.

In some embodiments of the foregoing aspects and embodiments, the metal chloride is copper chloride.

In one aspect, there are provided systems, comprising reactors configured to carry out the reactions of the preceding aspects and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention may be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

FIG. 1A is an illustration of some embodiments related to the methods and systems provided herein to form the PCH and the PO.

FIG. 1B is an illustration of some embodiments related to the methods and systems provided herein to form the PCH and the PO.

FIG. 2 is an illustration of some embodiments related to the formation of products from chlorination of propylene.

FIG. 3 is an illustration of some embodiments related to the methods and systems provided herein to form the PCH and the PO.

FIG. 4 is an illustration of some embodiments related to the methods and systems provided herein to form the PCH and the PO.

FIG. 5 is an illustration of some embodiments related to the methods and systems provided herein to form the PCH and the PO.

DETAILED DESCRIPTION

Disclosed herein are systems and methods that relate to producing propylene chlorohydrin and further propylene oxide in high yields with significantly less side products and/or waste materials.

Before the present invention is described in greater detail, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

Certain ranges that are presented herein with numerical values may be construed as “about” numericals. The “about” is to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately a specifically recited number, the near or approximating unrequited number may be a number, which, in the context in which it is presented, provides the substantial equivalent of the specifically recited number.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described.

All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.

It is noted that, as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order which is logically possible.

Methods and Systems

There are provided methods and systems that relate to the chlorination of propylene for the generation of one or more products comprising dichloropropane or 1,2-dichloropropane (DCP) and/or propylene chlorohydrin (PCH); hydrolysis of the DCP to the PCH; and further reaction of the PCH to form propylene oxide (PO). In some embodiments the chlorination is done using metal chloride solution with metal ions in higher oxidation state. There are also provided methods and systems for separation/purification of the products from the metal ion solution; regeneration of the metal chloride with metal ions in the higher oxidation state; recycling of the metal ion solution back to the chlorination reaction; and recycling of other side products.

Applicants have devised methods and systems to form the PCH and/or DCP in high yields and high selectivity where either the side products are not formed, or are formed in low yields, or are converted to the PCH, DCP, and/or propylene. Applicants have also devised methods and systems to convert the side products back either to the propylene or to the PCH such that the PCH is formed in high yield and with selectivity. Further Applicants have devised methods and systems to form the PO from the PCH in high yield and with high selectivity. Applicants have devised methods and systems to form the PO with reduced waste water, resulting in economical and environmentally friendly methods to form the PO.

The combination of methods and systems used to form the PCH from the propylene and further to form the PO relate to various combinations of an electrochemical method/system, a chlorination method/system, an oxychlorination method/system, a hydrolysis method/system, and an epoxidation method/system, to form the PO. The electrochemical and the chlorination methods and systems have been described in detail in U.S. patent application Ser. No. 13/474,598, filed May 17, 2012, issued as U.S. Pat. No. 9,187,834, on Nov. 17, 2015, which is incorporated herein by reference in its entirety. The oxychlorination and the epoxidation methods and systems have been described in U.S. patent application Ser. No. 15/963,637, filed Apr. 26, 2018, which is incorporated herein by reference in its entirety.

Illustrated in FIG. 1A is the block flow diagram for the formation of the PO from the propylene. In block 3, is shown an electrochemical reaction/cell where the metal ions of the metal halide in the lower oxidation state and the higher oxidation state are illustrated as CuCl (a mixture of CuCl and CuCl₂). Metal ions are oxidized from the lower oxidation state to the higher oxidation state at the anode where cathode reaction includes formation of sodium hydroxide. Other cathode reaction are also possible and are explained in detail in U.S. patent application Ser. No. 15/963,637, filed Apr. 26, 2018, which is incorporated herein by reference in its entirety. For example, in some embodiments, the cathode electrolyte comprises water and the cathode is an oxygen depolarizing cathode that reduces oxygen and water to hydroxide ions; the cathode electrolyte comprises water and the cathode is a hydrogen gas producing cathode that reduces water to hydrogen gas and hydroxide ions; the cathode electrolyte comprises hydrochloric acid and the cathode is a hydrogen gas producing cathode that reduces hydrochloric acid to hydrogen gas; or the cathode electrolyte comprises hydrochloric acid and the cathode is an oxygen depolarizing cathode that reacts hydrochloric acid and oxygen gas to form water.

The “metal ion” or “metal” or “metal ion in the metal chloride” or “metal ion in the metal halide” as used herein, includes any metal ion capable of being converted from lower oxidation state to higher oxidation state and vice versa. Examples of metal ions in the metal halide include, but are not limited to, iron, chromium, copper, tin, silver, cobalt, uranium, lead, mercury, vanadium, bismuth, titanium, ruthenium, osmium, europium, zinc, cadmium, gold, nickel, palladium, platinum, rhodium, iridium, manganese, technetium, rhenium, molybdenum, tungsten, niobium, tantalum, zirconium, hafnium, and combination thereof. In some embodiments, the metal ions include, but are not limited to, iron, copper, tin, chromium, or combination thereof. In some embodiments, the metal ion is copper. In some embodiments, the metal ion is tin. In some embodiments, the metal ion is iron. In some embodiments, the metal ion is chromium. In some embodiments, the metal ion is platinum. The “oxidation state” as used herein, includes degree of oxidation of an atom in a substance. For example, in some embodiments, the oxidation state is the net charge on the metal ion. The “halide” as used herein, includes fluoride, bromide, chloride, and iodide. For example only, metal halide includes metal chlorides such as, but not limited to, copper chloride (CuCl with Cu in the lower oxidation state of 1 and CuCl₂ with Cu in the higher oxidation state of 2).

As used herein, the “salt” or “saltwater” includes salt or salt in water where salt can be any alkali metal chloride or alkaline earth metal chloride, including but not limited to, sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride etc.

It is to be understood that the metal chloride with the metal ion in the lower oxidation state and the metal chloride with the metal ion in the higher oxidation state are both present in the aqueous medium in the electrochemical reaction/cell and the chlorination reaction/reactor. Owing to the reduction of the metal chloride from the higher oxidation state to the lower oxidation state in the chlorination reaction, the ratio of the metal chloride in the lower and the higher oxidation state are different in the aqueous medium entering the chlorination reaction and exiting the chlorination reaction. Suitable concentrations of the metal ions in the lower and higher oxidation state in the aqueous medium have been described herein. Some examples of the metal chlorides that may be used in the systems and methods include, but are not limited to, copper chloride, iron chloride, tin chloride, chromium chloride, zinc chloride, etc.

The anolyte from the anode chamber containing an aqueous stream of sodium chloride (any other salt may be used including but not limited to, alkali metal chloride such as potassium chloride or alkaline earth metal chloride such as calcium chloride), water and CuCl is then transferred to the chlorination reaction/reactor shown in block 1. In block 1, the propylene C₃H₆ is converted into the DCP and/or the PCH using copper chloride (II), simultaneously reducing two Cu(II) ions to Cu(I). The reactions are as shown below:

C₃H₆+2CuCl₂→ClCH₂CH(Cl)CH₃(DCP)+2CuCl  (I)

C₃H₆+2CuCl₂+H₂O→ClCH₂CH(OH)CH₃(PCH)+2CuCl+HCl  (II)

The “propylene chlorohydrin” or “PCH”, as used herein includes PCH in its isomeric form, such as, 1-chloro-2-propanol, 2-chloro-1-propanol, or both. Without being limited by any theory, both isomers may be formed and both may be subsequently converted to the PO. The explicit declaration of one isomer may not be construed as the absence of the other.

In block 2, some of the Cu(I) produced in block 1 is regenerated using chemical oxidation in oxychlorination reaction/reactor using oxidants such as, but not limited to, X₂ gas alone; or HX gas and/or HX solution in combination with gas comprising oxygen or ozone; or hydrogen peroxide; or HXO or salt thereof; or HXO₃ or salt thereof; or HXO₄ or salt thereof; or combinations thereof, wherein each X independently is a halogen selected from fluorine, chlorine, iodine, and bromine. For example, chlorine gas may be used to oxidize the metal halide from the lower to the higher oxidation state. For example, CuCl may be oxidized to CuCl₂ in the presence of chlorine gas as follows:

2CuCl+Cl₂→2CuCl₂  (III)

In some embodiments, the oxidant is HCl gas and/or HCl solution in combination with gas comprising oxygen. An example is as follows:

2CuCl+2HCl+½O₂→2CuCl₂+H₂O  (IV)

In some embodiments, the oxidant is HX gas and/or HX solution in combination with hydrogen peroxide, wherein X is a halogen. One example is as follows:

2CuCl+H₂O₂+2HCl→2CuCl₂+2H₂O  (V)

The oxidants have been described in U.S. patent application Ser. No. 15/963,637, filed Apr. 26, 2018, which is incorporated herein by reference in its entirety. Hydrochloric acid (HCl) is a common by-product in numerous chemical processes. One side product of the chlorination reaction of the propylene to the PCH is also HCl. The methods and systems provided herein can leverage the HCl in the oxychlorination step as a mechanism to provide additional copper oxidation. The HCl can also be sourced from other reactions and is labeled as “other HCl” in figures. The incorporation of HCl from chlorination reaction or other reactions may lead to additional PO production by upgrading these streams to more valuable products. The reuse of the HCl in oxychlorination process allows for the reduction of the base consumption to neutralize the acid which may improve overall economics, especially in cases where the base could otherwise be sold.

It is to be understood that the processes illustrated in FIG. 1A, such as electrochemical reaction, chlorination reaction, and the oxychlorination reaction, may each be individually carried out or may be in combination with one or more other processes. For example, the electrochemically generated CuCl₂ may be used in one reactor for the chlorination of the propylene to the PCH and/or the DCP and the chemically generated CuCl₂ (via oxychlorination) may be used in another propylene chlorination reactor each with the option of making the PCH directly or making the DCP with subsequent conversion to the PCH, all such configurations are within the scope of the present disclosure.

In one aspect, the oxychlorination reaction/reactor oxidizes the metal ion of the metal chloride in the lower oxidation state to the higher oxidation state in the presence of the oxidant (and in the absence of any electrochemical reaction/cell) and then the metal chloride with the metal ion in the higher oxidation state is then transferred to the chlorination reaction/reactor to chlorinate propylene, as illustrated in FIG. 1B. In block 2, is shown an oxychlorination reaction/reactor where the metal ions of the metal halide in the lower oxidation state and the higher oxidation state are illustrated as CuCl (a mixture of CuCl and CuCl₂). Metal ions are oxidized from the lower oxidation state to the higher oxidation state in the oxychlorination reaction/reactor. The solution from the oxychlorination reaction/reactor containing CuCl_(x) is then transferred to the chlorination reaction/reactor shown in block 1. In block 1, the propylene C₃H₆ is converted into the DCP and/or the PCH using copper chloride (II), simultaneously reducing two Cu(II) ions to Cu(I). It is to be understood that the electrochemical reaction/cell and the oxychlorination reaction/reactor may independently be carried out for the oxidation of the metal chloride (such as FIG. 1B for the oxychlorination reaction/reactor) or may be carried out in combination (such as FIG. 1A).

As shown in FIG. 1A, additional oxidation of the metal ion from the lower oxidation state to the higher oxidation state, e.g. CuCl to CuCl₂, may be done electrochemically in block 3. Overall, the oxidation done in blocks 2 and 3 may equal the amount of reduction accomplished in 1. The flow of copper chloride between the electrochemical, chlorination, and the oxychlorination systems may be either clockwise or counter clockwise as indicated by the circular arrows. That is, the order of operations between the three units is flexible. The propylene chlorohydrin formed in 1 is converted to propylene oxide in the epoxidation reaction/reactor shown as block 4. The reaction is as shown below:

ClCH₂CH(OH)CH₃+NaOH→H₂C(O)CHCH₃(PO)+NaCl+H₂O  (VI)

In order to improve the yield and selectivity (or space time yield (STY)) of the PO, it is essential to form the PCH with high yield and high selectivity. The methods and system herein provide various ways to form the PCH with high yield and high selectivity and to subsequently also form the PO with high yield and high selectivity.

Forming the PCH Under Reaction Conditions

In one aspect, there are provided methods that include chlorinating propylene in an aqueous medium comprising metal chloride with metal ion in higher oxidation state and salt under reaction conditions to result in one or more products comprising PCH, and the metal chloride with the metal ion in lower oxidation state. The chlorination reaction may take place after the electrochemical reaction and/or the oxychlorination reaction.

In some embodiments, there are provided methods that include (i) contacting an anode with an anode electrolyte in an electrochemical cell wherein the anode electrolyte comprises metal chloride and saltwater; contacting a cathode with a cathode electrolyte in the electrochemical cell; applying voltage to the anode and the cathode and oxidizing the metal chloride with metal ion in a lower oxidation state to a higher oxidation state at the anode; and (ii) withdrawing the anode electrolyte from the electrochemical cell and chlorinating propylene with the anode electrolyte comprising the metal chloride with the metal ion in the higher oxidation state in the saltwater under reaction conditions to result in one or more products comprising PCH and the metal chloride with the metal ion in the lower oxidation state.

In some embodiments, there are provided methods that include (i) oxidizing metal chloride with metal ion in a lower oxidation state to a higher oxidation state in presence of an oxidant in an oxychlorination reaction; and (ii) withdrawing the metal chloride with metal ion in the higher oxidation state from the oxychlorination reaction and chlorinating propylene with the metal chloride with the metal ion in the higher oxidation state in saltwater under reaction conditions to result in one or more products comprising PCH and the metal chloride with the metal ion in the lower oxidation state.

In some embodiments of the aforementioned aspect and embodiments, the methods further include (iii) epoxidizing the PCH with a base to form PO.

An illustration of the chlorination reaction is shown in FIG. 2. In some embodiments, the propylene may be supplied under pressure in the liquid phase and/or the gas phase and the metal chloride, for example only, copper (II) chloride (also containing copper (I) chloride) is supplied in an aqueous solution such as saltwater. The reaction may occur in the liquid phase where the dissolved propylene reacts with the copper (II) chloride. As illustrated in FIG. 2, the chlorination of the propylene in the presence of the metal chloride with the metal ion in the higher oxidation state (e.g. CuCl₂) may result in one or more products such as, but not limited to, PCH, DCP, isopropanol, and isopropyl chloride. Applicants have found that in order to form the PCH in high space time yield (to minimize reactor costs) with high selectivity (to minimize propylene costs) certain reactions conditions may be controlled and used. Such reaction conditions include, but are not limited to, temperature and pressure in the chlorination reaction; use of the other DCP; use of metal hydroxychloride; amount of salt; amount of total chloride content; residence time of the chlorination mixture; presence of a noble metal; etc.

In some embodiments of all of the aforementioned aspect and embodiments, the PCH is formed with selectivity of between about 20-100%; or between about 20-90%; or between about 20-80%; or between about 20-70%; or between about 20-60%; or between about 20-50%; or between about 20-40%; or between about 30-100%; or between about 30-90%; or between about 30-80%; or between about 30-70%; or between about 30-60%; or between about 30-50%; or between about 30-40%; or between about 40-100%; or between about 40-90%; or between about 40-80%; or between about 40-70%; or between about 40-60%; or between about 40-50%; or between about 75-100%; or between about 75-90%; or between about 75-80%; or between about 90-100%; or between about 90-99%; or between about 90-95%. In some embodiments, the above noted selectivity is in wt %.

In some embodiments, the STY (space time yield) of the one or more products from propylene and/or DCP, e.g. the STY of PCH is 0.01, or 0.05, or less than 0.1, or more than 0.1, or more than 0.5, or is 1, or more than 1, or more than 2, or more than 3, or more than 4, or between 0.01-0.05, or between 0.01-0.1, or between 0.1-3, or between 0.5-3, or between 0.5-2, or between 0.5-1, or between 3-5. As used herein the STY is yield per time unit per reactor volume. For example, the yield of product may be expressed in mol, the time unit in hour and the volume in liter. The volume may be the nominal volume of the reactor, e.g. in a packed bed reactor, the volume of the vessel that holds the packed bed is the volume of the reactor. The STY may also be expressed as STY based on the amount of propylene consumed and/or based on amount of the DCP consumed to form the product. For example only, in some embodiments, the STY of the PCH product may be deduced from the amount of propylene consumed and/or based on amount of the DCP consumed during the reaction. The selectivity may be the mol of product, e.g. PCH/mol of the propylene consumed and/or PCH/mol of the DCP consumed. The yield may be the amount of the product isolated. The purity may be the amount of the product/total amount of all products (e.g., amount of PCH/all the organic products formed).

Various suitable reaction conditions to form PCH have been described herein below.

The “other DCP” or “other sources of DCP” as mentioned herein (and illustrated in figures) includes DCP formed as a by-product of other processes. Examples of the other processes or sources include, but are not limited to, the traditional chlorohydrin route to the PO or the DCP formed by the chlorination of the propylene with chlorine. This stream is labeled as “other DCP” in figures, which illustrates the various locations in the process where this stream may be incorporated into the process. The incorporation of this other DCP can lead to additional PCH and PO production by upgrading these streams to more valuable products.

In the traditional chlorohydrin process, the PCH may be formed through the addition of hypochlorous acid (HOCl) to the propylene. The HOCl may itself be formed by the addition of chlorine (Cl₂) to water, a reaction which co-produces a stoichiometric amount of hydrochloric acid (HCl). To minimize reactions of the propylene with both HCl and the direct addition of Cl₂ across the double bond, the reactor may be operated under very dilute concentrations of HOCl and with an equivalent of base (in the form of NaOH or CaO) to neutralize the HCl. Even under these conditions, the formation of unwanted DCP can be significant, representing a propylene selectivity loss on the order of 10%. This unwanted DCP can be used as the other DCP in the methods described herein and provide an economic use of a waste stream.

Another source of DCP (the “other DCP”) is the production of the DCP through the direct addition of chlorine to the propylene. New or existing sources of chlorine (such as, but not limited to, Deacon process and the chlor-alkali process) may be used to make the DCP via direct chlorination of the propylene, similar to the process used industrially to make ethylene dichloride from ethylene and chlorine. This DCP formed via direct chlorination may then be converted to the PCH using methods provided herein and ultimately form the PO. The HCl formed as a by-product from the conversion to the PCH would then be captured and reused.

Such methods and systems for other sources of DCP may be integrated with the methods and systems provided herein to hydrolyze the DCP formed as a major product or as a waste stream to the PCH and then to the PO.

In some embodiments of the foregoing aspect and embodiments, reaction conditions for the chlorination reaction comprise temperature between 100-150° C., pressure between 125-350 psig, or combination thereof.

In some embodiments of the aforementioned aspect and embodiments, the methods to form PCH comprise reaction conditions, such as, but not limited to, use of metal hydroxychloride. Without being limited by any theory, it is contemplated that the metal chloride may react with water and oxygen to form metal hydroxychloride species of stoichiometry M_(x) ^(n+)Cl_(y)(OH)_((nx-y)), M_(x)Cl_(y)(OH)_((2x-y)), M_(x)Cl_(y)(OH)_((3x-y)) or M_(x)Cl_(y)(OH)_((4x-y)), where M is the metal ion. An illustration of the reaction is as shown below (VII) taking copper chloride as an example:

2CuCl+H₂O+½O₂→2CuClOH  (VII)

Where the CuClOH species represents one of many possible copper hydroxychloride species of stoichiometry Cu_(x)Cl_(y)(OH)_((2x-y)). If in reaction with the propylene, the CuCl₂ is replaced (e.g. at least partially) by a hydroxychloride, the following reaction (VIII) may take place:

C₃H₆(propylene)+CuClOH+CuCl₂→ClCH₂CH(OH)CH₃(PCH)+2CuCl  (VIII)

This reaction may allow for improved selectivity for the PCH vs. the other products such as the DCP. The reaction with the oxygen to form the metal hydroxychloride species of stoichiometries as noted above, may occur in a reactor separate from the chlorination reactor or may occur in the chlorination reactor during the chlorination of the propylene. Other examples of the metal hydroxychloride, without limitation include, MoCl(OH)₃, MoCl₂(OH)₂, and MoCl₃(OH).

In some embodiments of the aforementioned aspect and embodiments, the reaction conditions in the methods to form the PCH comprise chlorinating in between about 1-30 wt % salt. The salt may be between 1-30 wt %; or between 5-30 wt % salt; or between about 8-30 wt %; or between 10-30 wt %; or between 15-30 wt %; r between 20-30 wt %; or between 5-10 wt %. “Salt” as used herein includes its conventional sense to refer to a number of different types of salts including, but not limited to, alkali metal chlorides such as, sodium chloride, potassium chloride, lithium chloride, cesium chloride, etc.; alkaline earth metal chlorides such as, calcium chloride, strontium chloride, magnesium chloride, barium chloride, etc; or ammonium chloride. In some embodiments of the foregoing aspects and embodiments, the salt comprises alkali metal chloride or alkaline earth metal chloride. In some embodiments, the salt (for example only, sodium chloride or calcium chloride) in the chlorination includes between about 1-30 wt % salt; or between 1-25 wt % salt; or between 1-20 wt % salt; or between 1-10 wt % salt; or between 5-30 wt % salt; or between 5-20 wt % salt; or between 5-10 wt % salt; or between about 8-30 wt % salt; or between about 8-25 wt % salt; or between about 8-20 wt % salt; or between about 8-15 wt % salt; or between about 10-30 wt % salt; or between about 10-25 wt % salt; or between about 10-20 wt % salt; or between about 10-15 wt % salt; or between about 15-30 wt % salt; or between about 15-25 wt % salt; or between about 15-20 wt % salt; or between about 20-30 wt % salt; or between about 20-25 wt % salt.

In some embodiments, the aqueous medium for the chlorination reaction may contain between 5-50%; or 5-40%; or 5-30%; or 5-20%; or 5-10%; or 50-75%; or 50-70%; or 50-65%; or 50-60% by weight of water in the aqueous medium depending on the amount of salt and the metal halide.

In some embodiments of the aforementioned aspect and embodiments, the reaction conditions in the methods to form the PCH comprise chlorinating in aqueous medium with total chloride content of between about 10-30 wt %. The total chloride content is a combination of chloride from the metal chloride as well as the chloride from the salt. Applicants surprisingly observed that chlorination in the aqueous medium with total chloride content between about 10-30 wt % resulted in high yield and high selectivity of the PCH over other side products.

In some embodiments, the reaction conditions in the methods to form the PCH comprise varying the incubation time or residence time or mean residence time of the chlorination mixture. The “incubation time” or “residence time” or “mean residence time” as used herein includes the time period for which the chlorination mixture is left in the reactor at the above noted temperatures before being taken out for the separation of the product. In some embodiments, the residence time for the chlorination mixture is few seconds or between about 1 sec-1 hour; or 1 sec-10 hours; or 10 min-10 hours or more depending on the temperature of the chlorination mixture. This residence time may be in combination with other reaction conditions such as, e.g. the temperature ranges and/or total chloride concentrations provided herein. In some embodiments, the residence time for the chlorination mixture is between about 1 sec-3 hour; or between about 1 sec-2.5 hour; or between about 1 sec-2 hour; or between about 1 sec-1.5 hour; or between about 1 sec-1 hour; or 10 min-3 hour; or between about 10 min-2.5 hour; or between about 10 min-2 hour; or between about 10 min-1.5 hour; or between about 10 min-1 hour; or between about 10 min-30 min; or between about 20 min-3 hour; or between about 20 min-2 hour; or between about 20 min-1 hour; or between about 30 min-3 hour; or between about 30 min-2 hour; or between about 30 min-1 hour; or between about 1 hour-2 hour; or between about 1 hour-3 hour; or between about 2 hour-3 hour, to form the PCH as noted herein.

In some embodiments, the reaction conditions in the methods to form the PCH include carrying out the chlorination in the presence of a noble metal. The “noble metal” as used herein includes metals that are resistant to corrosion in moist conditions. In some embodiments, the noble metals are selected from ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold, mercury, rhenium, titanium, niobium, tantalum, and combinations thereof. In some embodiments, the noble metal is selected from rhodium, palladium, silver, platinum, gold, titanium, niobium, tantalum, and combinations thereof. In some embodiments, the noble metal is palladium, platinum, titanium, niobium, tantalum, or combinations thereof. In some embodiments, the foregoing noble metals may be present in 0, +2 or +4 oxidation states as appropriate. For example only, platinum or palladium may be present as metal or as a metal over carbon or may be present as PtCl₂ or PdCl₂ etc. In some embodiments, the foregoing noble metal is supported on a solid. Examples of solid support include, without limitation, carbon, zeolite, titanium dioxide, alumina, silica, and the like. In some embodiments, the foregoing noble metal is supported on carbon. For example only, the catalyst is palladium or palladium over carbon. The amount of nobel metal used in the chlorination reaction is between 0.001M to 2M; or between 0.001-1.5M; or between about 0.001-1M; or between about 0.001-0.5M; or between about 0.001-0.05M; or between 0.01-2M; or between 0.01-1.5M; or between 0.01-1M; or between 0.01-0.5M; or between 0.1-2M; or between 0.1-1.5M; or between 0.1-1M; or between 0.1-0.5M; or between 1-2M.

In some embodiments of the foregoing aspect and embodiments, the method to form the PCH further comprises adding platinum or palladium to the aqueous medium. In some embodiments of the foregoing aspect and embodiments, the platinum or palladium is in concentration of between about 0.001-0.1M.

In some embodiments of the foregoing aspects and embodiments, total amount of chloride content in the aqueous medium is between 4-15M or 4-10M. In some embodiments of the foregoing aspects and embodiments, the aqueous medium in the chlorination reaction comprises the metal chloride in the higher oxidation state in range of 0.1-5M or 1-5M, or 1.5-5M, the metal chloride in the lower oxidation state in range of 0.1-2M, and the sodium chloride in range of 0.1-5M or 1-5M.

Forming the PCH from the DCP

As illustrated in FIG. 2, DCP may be another product formed after the chlorination of propylene. The “1,2-dichloropropane” or “dichloropropane” or “propylene dichloride” or “DCP” or “PDC” can be used interchangeably. In some embodiments, the DCP may be formed as a major product and in one aspect, there are provided methods and systems to convert the DCP to the PCH in the same or a separate reactor.

In one aspect, there are provided methods that include chlorinating propylene in an aqueous medium comprising metal chloride with metal ion in higher oxidation state and salt under reaction conditions to result in one or more products comprising DCP, and the metal chloride with the metal ion in lower oxidation state; and hydrolyzing the DCP to PCH. In some embodiments of the foregoing aspect, the one or more products further comprise PCH. In some embodiments of the foregoing aspect and embodiments, the method comprises one or more of (A) hydrolyzing the DCP to the PCH in situ; (B) separating the DCP from the aqueous medium and/or from the PCH (when both DCP and PCH are formed in the chlorination reaction) and hydrolyzing the DCP to the PCH; and/or (C) hydrolyzing the DCP to the PCH without the separation of the DCP from the PCH and/or from the aqueous medium, to increase the yield of the PCH. The electrochemical reaction/cell, the chlorination reaction/reactor, the oxychlorination reaction/reactor, the hydrolysis reaction/reactor, and the epoxidation reaction/reactor are all illustrated in FIG. 3.

The chlorination reaction may take place after the electrochemical reaction and/or the oxychlorination reaction. Accordingly, in some embodiments there are provided methods that include (i) contacting an anode with an anode electrolyte in an electrochemical cell wherein the anode electrolyte comprises metal chloride and saltwater; contacting a cathode with a cathode electrolyte in the electrochemical cell; applying voltage to the anode and the cathode and oxidizing the metal chloride with metal ion in a lower oxidation state to a higher oxidation state at the anode; (ii) withdrawing the anode electrolyte from the electrochemical cell and chlorinating propylene with the anode electrolyte comprising the metal chloride with the metal ion in the higher oxidation state in the saltwater to result in one or more products comprising DCP and the metal chloride with the metal ion in the lower oxidation state; and (iii) hydrolyzing the DCP to the PCH. In some embodiments, there are provided methods that include (i) oxidizing metal chloride with metal ion in a lower oxidation state to a higher oxidation state in presence of an oxidant in an oxychlorination reaction; (ii) withdrawing the metal chloride with metal ion in the higher oxidation state from the oxychlorination reaction and chlorinating propylene with the metal chloride with metal ion in the higher oxidation state in saltwater to result in one or more products comprising DCP and the metal chloride with the metal ion in the lower oxidation state; and (iii) hydrolyzing the DCP to the PCH. In some embodiments of the foregoing aspect and embodiments, the one or more products further comprise PCH. In some embodiments of the foregoing aspect and embodiments, the method further comprises one or more of (A) hydrolyzing the DCP to the PCH in situ; (B) separating the DCP from the aqueous medium and/or from the PCH and then hydrolyzing the DCP to the PCH; and/or (C) hydrolyzing the DCP to the PCH without the separation of the DCP from the PCH and/or the aqueous medium, to increase the yield of the PCH. In some embodiments of the aforementioned embodiments, the methods further include (iv) epoxidizing the PCH with a base to form PO.

In one aspect, there is provided a system comprising (i) an electrochemical cell comprising an anode chamber comprising an anode and an anode electrolyte wherein the anode electrolyte comprises metal chloride and saltwater and anode is configured to oxidize metal chloride with metal ion in a lower oxidation state to a higher oxidation state; a cathode chamber comprising a cathode and a cathode electrolyte; and a voltage source configured to apply voltage to the anode and the cathode; (ii) a chlorination reactor operably connected to the anode chamber of the electrochemical cell and configured to obtain the anode electrolyte and chlorinate propylene with the anode electrolyte comprising the metal chloride with the metal ion in the higher oxidation state in the saltwater to result in one or more products comprising DCP and the metal chloride with the metal ion in the lower oxidation state; (iii) a hydrolysis reactor operably connected to the chlorination reactor and configured to obtain the one or more products comprising DCP from the chlorination reactor with or without the saltwater comprising metal chloride and configured to hydrolyze the DCP to the PCH; and (iv) an epoxidation reactor operably connected to the hydrolysis reactor and configured to obtain the solution comprising DCP and PCH and epoxidize the PCH to PO in presence of a base. In some embodiments, the system further comprises an oxychlorination reactor operably connected to the chlorination reactor and/or the electrochemical cell, and the hydrolysis reactor and configured to obtain aqueous medium from the chlorination reactor and/or the electrochemical cell comprising the metal chloride with metal ion in the lower oxidation state and the higher oxidation state and obtain HCl produced in the hydrolysis reactor and configured to oxidize the metal chloride with metal ion in the lower oxidation state to the higher oxidation state using an oxidant comprising the HCl and oxygen, or hydrogen peroxide (or any other oxidant as described herein).

In one aspect, the oxychlorination reactor is used independent of the electrochemical cell. In some embodiments, there is provided a system comprising (i) oxychlorination reactor configured to oxidize metal chloride with metal ion in lower oxidation state to higher oxidation state using an oxidant comprising HCl and oxygen, or hydrogen peroxide (or any other oxidant as described herein); (ii) a chlorination reactor operably connected to the oxychlorination reactor and configured to obtain the metal chloride with the metal ion in the higher oxidation state and chlorinate propylene with the metal chloride with the metal ion in the higher oxidation state in saltwater to result in one or more products comprising DCP and the metal chloride with the metal ion in the lower oxidation state; (iii) a hydrolysis reactor operably connected to the chlorination reactor and configured to obtain the one or more products comprising DCP from the chlorination reactor with or without the saltwater comprising metal chloride and configured to hydrolyze the DCP to the PCH; and (iv) an epoxidation reactor operably connected to the hydrolysis reactor and configured to obtain the solution comprising DCP and PCH and epoxidize the PCH to PO in presence of a base. In some embodiments, the oxychlorination reactor is also operably connected to the chlorination reactor and the hydrolysis reactor and is configured to obtain the aqueous medium from the chlorination reactor comprising the metal chloride with metal ion in the lower oxidation state and the higher oxidation state and is configured to obtain HCl produced in the hydrolysis reactor.

In some embodiments, the conversion of the DCP to the PCH is a hydrolysis reaction:

ClCH₂CH(Cl)CH₃+H₂O→ClCH₂CH(OH)CH₃+HCl  (IX)

ClCH₂CH(Cl)CH₃+H₂O→HOCH₂CH(Cl)CH₃+HCl  (X)

In reactions (IX) and (X) above, the DCP is hydrolyzed by water into two isomers of the PCH: 1-chloro-2-propanol and 2-chloro-1-propanol. The conversion of the DCP to the PCH is slow at room temperature. In some embodiments, there are provided efficient methods to convert the DCP to the PCH by hydrolysis.

In some embodiments, the reaction conditions listed in the foregoing section also aid in (A) the hydrolysis of the DCP to the PCH in situ (e.g. during chlorination reaction in the chlorination reactor). The DCP may be hydrolyzed to the PCH in situ by increasing the available free water during the reaction. Because water is a reactant in the hydrolysis of the DCP to the PCH, the presence of free water may lead to the conversion of the DCP to the PCH.

In some embodiments, the DCP may be formed in high yield and may then be hydrolyzed to the PCH (B and C above). In such embodiments, some amount of PCH may be formed in the chlorination reaction which may or may not be separated from the DCP. There may be a number of options to increase the rate and/or selectivity of the DCP formation. These options include highly concentrated salt solutions which reduce the available free water. Because water is a reactant in the hydrolysis of the DCP to the PCH, the presence of free water may lead to the conversion of the DCP to the PCH. The high concentrations of salt may be accomplished through the addition of the copper chloride salts (such as CuCl₂, CuCl or in combination) or through other salts such as NaCl. There are also a number of process conditions which can be optimized to provide higher STY and better selectivity for the DCP production including temperature, pressure (e.g. pressures under which the propylene may form a liquid or supercritical phase), and residence time.

In one aspect, the conversion of the DCP to the PCH may be executed in a second reaction step downstream (in a separate reactor) of the propylene chlorination, illustrated as the hydrolysis reactor in FIG. 3. The DCP may be hydrolyzed to the PCH by (B) separating the DCP from the aqueous medium and/or from the PCH (when both DCP and PCH are formed in the chlorination reaction) and then hydrolyzing the DCP to the PCH; and/or (C) hydrolyzing the DCP to the PCH without the separation of the DCP from the PCH and/or the aqueous medium, to increase the yield of the PCH. When the hydrolysis is done in a second step, the hydrolysis of the DCP to the PCH may utilize the aqueous stream leaving the chlorination reaction/reactor (containing the aqueous metal chloride, e.g. aqueous copper chloride) as part of a circulating loop (embodiment C above related to hydrolysis without the separation of the DCP from the aqueous medium). Illustrated in FIG. 3 is the aspect where the DCP is converted to the PCH in a hydrolysis reaction/reactor after the chlorination reaction/reactor.

FIG. 3 illustrates that the chlorination is divided among two reaction blocks. Block 1 effects propylene chlorination to one or more products comprising the DCP (and optionally the PCH too). Block 5 in FIG. 3 uses the aqueous copper chloride stream from block 1 and hydrolyzes the DCP to the PCH. To leverage the process economics of the conversion of the DCP to the PCH in an optimum way, the process may recover at least some of the HCl by-product from the hydrolysis of the DCP to the PCH (equations IX and X above). This HCl can be reused in a traditional oxychlorination reaction for the production of ethylene dichloride (EDC) or used in the oxychlorination unit 2 within the process to generate additional PO.

In some embodiments of the above noted aspect, the method comprises (B) separating the DCP from the aqueous medium and/or from the PCH and then hydrolyzing the DCP to the PCH. In such embodiments, a separation step takes place between the chlorination and the hydrolysis. In one aspect, there are provided methods to form PCH, comprising: (i) contacting an anode with an anode electrolyte in an electrochemical cell wherein the anode electrolyte comprises metal chloride and saltwater; contacting a cathode with a cathode electrolyte in the electrochemical cell; applying voltage to the anode and the cathode and oxidizing the metal chloride with metal ion in a lower oxidation state to a higher oxidation state at the anode; (ii) withdrawing the anode electrolyte from the electrochemical cell and chlorinating propylene in the anode electrolyte comprising metal chloride with metal ion in higher oxidation state and the saltwater to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state; (iii) separating the PCH from the aqueous medium; and (iv) treating the aqueous medium comprising the metal chloride with metal ions in the higher oxidation state and the lower oxidation state and the DCP with water to hydrolyze the DCP to the PCH. In one aspect, there are provided methods to form PCH, comprising: (i) oxidizing metal chloride with metal ion in a lower oxidation state to a higher oxidation state in presence of an oxidant in an oxychlorination reaction; (ii) withdrawing the metal chloride with metal ion in the higher oxidation state from the oxychlorination reaction and chlorinating propylene with the metal chloride with the metal ion in the higher oxidation state in saltwater under reaction conditions to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state; (iii) separating the PCH from the aqueous medium; and (iv) treating the aqueous medium comprising the metal chloride with metal ions in the higher oxidation state and the lower oxidation state and the DCP with water to hydrolyze the DCP to the PCH. In some embodiments of the foregoing aspects, the methods further include (v) epoxidizing the PCH with a base to form propylene oxide (PO). The PCH may be separated from the aqueous stream using various separation techniques, including, but not limited to, reactive separation, distillation, molecular sieve, membrane, etc.

In another aspect, both the DCP and the PCH are separated from the aqueous stream and the DCP is hydrolyzed to the PCH in the absence of the metal salts used in the chlorination of the propylene (e.g. metal chlorides used in the chlorination of propylene). Accordingly, in one aspect, there are provided methods to form PCH, comprising: (i) contacting an anode with an anode electrolyte in an electrochemical cell wherein the anode electrolyte comprises metal chloride and saltwater; contacting a cathode with a cathode electrolyte in the electrochemical cell; applying voltage to the anode and the cathode and oxidizing the metal chloride with metal ion in a lower oxidation state to a higher oxidation state at the anode; (ii) withdrawing the anode electrolyte from the electrochemical cell and chlorinating propylene in the anode electrolyte comprising metal chloride with metal ion in higher oxidation state to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state; (iii) separating organics comprising the PCH and the DCP from the aqueous medium comprising the metal chloride with metal ions in the higher oxidation state and the lower oxidation state; and (iv) hydrolyzing the DCP (also containing PCH) with water to form the PCH. In one aspect, there are provided methods to form PCH, comprising: (i) oxidizing metal chloride with metal ion in a lower oxidation state to a higher oxidation state in presence of an oxidant in an oxychlorination reaction; (ii) withdrawing the metal chloride with metal ion in the higher oxidation state from the oxychlorination reaction and chlorinating propylene with the metal chloride with the metal ion in the higher oxidation state in saltwater under reaction conditions to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state; (iii) separating organics comprising the PCH and the DCP from the aqueous medium comprising the metal chloride with metal ions in the higher oxidation state and the lower oxidation state; and (iv) hydrolyzing the DCP (also containing PCH) with water to form the PCH.

In some embodiments of the foregoing aspects, the DCP is separated from the PCH before the hydrolysis step. In some embodiments of the foregoing aspects, the method further includes (v) epoxidizing the PCH with a base to form propylene oxide (PO).

In some embodiments, the hydrolysis step forms HCl and the method further comprises recirculating the HCl to the oxychlorination step (illustrated in FIG. 3) where the metal chloride with the metal ion in the lower oxidation state is converted to the metal chloride with the metal ion in the higher oxidation state in presence of the HCl and oxygen, or hydrogen peroxide, or any other oxidant described herein.

In some embodiments, the chlorination reaction may be run in reaction conditions, such as, at elevated temperatures and at lower metal chloride concentration. In such embodiments, both the PCH and the DCP may be separated from the aqueous medium comprising metal chloride as stated above.

In some embodiments, the step of separating the one or more products comprising DCP from the chlorination reaction comprises any separation method known in the art. In some embodiments, the one or more products comprising DCP and optionally the PCH may be separated from the chlorination reaction as a vapor stream. The separated vapors may be cooled and/or compressed and subjected to the hydrolysis reaction. Other separation methods include, without limitation, distillation and/or flash distillation using the distillation column or flash distillation column. The remaining one or more products comprising DCP and optionally the PCH in the aqueous medium may be further separated using methods such as, decantation, extraction, or combination thereof. Various examples of the separation methods are described in detail in U.S. patent application Ser. No. 14/446,791, filed Jul. 30, 2014, which is incorporated herein by reference in its entirety.

In one aspect, the DCP may be used as an extraction solvent that extracts DCP and the PCH from the aqueous stream from the chlorination reaction/reactor. The DCP used as the extraction solvent can be DCP from the same process that has been separated and recirculated and/or is the other DCP. The “other DCP” has been described herein. The extraction solvent can be any organic solvent that removes DCP and/or the PCH from the aqueous metal ion solution. Applicants surprisingly found that in some embodiments, the use of DCP as the extraction solvent may ensure that the hydrolysis reaction, which occurs in an aqueous solution with metal chlorides (aspect above) or without metal chlorides (another aspect above), can have the maximum rate as the aqueous medium can be saturated with the DCP. In some embodiments, the DCP may be present in excess amount in order to facilitate efficient hydrolysis. In some embodiments, the mol % of the DCP is equal to or greater than the mol % of the PCH. In some embodiments, the DCP may be as high as 10-95% by volume; or 10-90% by volume; or 10-80% by volume; or 10-70% by volume; or 10-60% by volume; or 10-50% by volume; or 10-40% by volume; or 10-30% by volume; or 10-20% by volume, of the total solution volume. There may be several benefits to the use of DCP as the extraction solvent. The DCP can form a second organic phase which may help ensure that a soluble concentration of DCP remains in the aqueous phase. In some embodiments, further degradation of the PCH into other products (such as, but not limited to, acetone and/or propylene glycol) may be minimized as the PCH may preferentially partition into the DCP phase rather than the aqueous phase. In a continuous operation, the PCH may be removed from the reactor in the organic phase with the un-reacted DCP. This last advantage may alleviate the need to separate the PCH from the aqueous solution by other techniques such as distillation. By extracting the PCH with the DCP, the PCH can be removed from the chlorination reactor by removing the DCP layer that is phase-separated from the aqueous layer.

FIG. 4 illustrates an example of the use of the DCP as an extracting solvent. In FIG. 4, the recirculating DCP stream serves to extract the PCH both from the propylene chlorination reactor (block 1) and the hydrolysis reactor (block 5). The PCH recovered from these reactors along with the DCP may be then sent to epoxidation, where the PCH is converted to the PO and the DCP stream is recirculated. In this configuration, any DCP made in the propylene chlorination reactor may be balanced by conversion to the PCH in the hydrolysis reactor. The extracting solvent as shown in FIG. 4 can flow either clockwise or counterclockwise. The order of operations may be determined by process economics. The epoxidation of the PCH to the PO in the presence of the DCP has been described below in detail.

In some embodiments, the DCP as the extraction solvent is the DCP separated and recirculated from the same process (as illustrated in FIG. 4) and/or is other DCP from other sources. The process using the other DCP is as illustrated in FIG. 5. In this embodiment, new or existing sources of chlorine to make the DCP via direct chlorination of propylene, shown as block 7 in FIG. 5, is connected to the chlorination reactor and/or the hydrolysis reactor for the DCP to be converted to the PCH and ultimately to the PO. The HCl formed as a by-product from the conversion to the PCH would then be captured and reused. The direct chlorination reactor such as traditional chlorohydrin process and/or direct chlorination of propylene with chlorine may replace or supplement the electrochemical and/or the oxychlorination processes provided herein (oxychlorination shown as block 2 in FIG. 5).

Accordingly, in one aspect, there are provided methods to form PCH, comprising: (i) contacting an anode with an anode electrolyte in an electrochemical cell wherein the anode electrolyte comprises metal chloride and saltwater; contacting a cathode with a cathode electrolyte in the electrochemical cell; applying voltage to the anode and the cathode and oxidizing the metal chloride with metal ion in a lower oxidation state to a higher oxidation state at the anode; (ii) withdrawing the anode electrolyte from the electrochemical cell and chlorinating propylene in the anode electrolyte comprising metal chloride with metal ion in higher oxidation state to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state; (iii) extracting the one or more products comprising PCH and DCP from the aqueous medium by extracting with DCP as an extraction solvent; and (iv) hydrolyzing the DCP with water to form the PCH. In one aspect, there are provided methods to form PCH, comprising: (i) oxidizing metal chloride with metal ion in a lower oxidation state to a higher oxidation state in presence of an oxidant in an oxychlorination reaction; (ii) withdrawing the metal chloride with metal ion in the higher oxidation state from the oxychlorination reaction and chlorinating propylene with the metal chloride with the metal ion in the higher oxidation state in saltwater under reaction conditions to result in one or more products comprising PCH and DCP, and the metal chloride with the metal ion in lower oxidation state; (iii) extracting the one or more products comprising PCH and DCP from the aqueous medium by extracting with DCP as an extraction solvent; and (iv) hydrolyzing the DCP with water to form the PCH.

It is to be understood that in all the aspects and embodiments provided herein, the anode electrolyte withdrawn from the electrochemical cell and/or the metal chloride with metal ion in the higher oxidation state withdrawn from the oxychlorination reaction, comprise both the metal chloride with the metal ion in the lower oxidation state as well as the metal chloride with the metal ion in the higher oxidation state (e.g. CuCl_(x)).

In some embodiments, the method further includes after extraction, transferring aqueous medium comprising the metal chloride with metal ions in the higher oxidation state and the lower oxidation state to the oxychlorinating reaction/reactor; to the hydrolysis reaction/reactor; to the chlorination reaction/reactor; and/or to the electrochemical reaction/cell.

In some embodiments, the temperature and the residence time in the hydrolysis reaction/reactor may be different from the one in the chlorination reaction/reactor. For example, in some embodiments, the hydrolysis reaction may be run at a lower temperature than the chlorination reaction. Also, in some embodiments, the residence time in the hydrolysis reaction may be longer than that in the chlorination reaction. The extraction method may be such that once the one or more products comprising DCP and PCH are extracted from the aqueous medium using the DCP as an extraction solvent, the organics are transferred to the hydrolysis reaction; the aqueous stream comprising metal chloride with metal ions in the higher oxidation state and the lower oxidation state is added back to the hydrolysis reaction; and the reaction is run at lower temperature and longer residence time so that the DCP is hydrolyzed to the PCH. This may avoid more DCP being formed and/or more PCH decomposing to form other side products in the chlorination reaction.

In some embodiments of the above noted aspect, the method further includes (v) transferring the organic medium comprising PCH and DCP (remaining if any, after the hydrolyis) from the hydrolyzing step to epoxidation; and (vi) epoxidizing the PCH with a base to form PO in the presence of the DCP (described in detail further herein below).

In some embodiments of the above noted aspects and embodiments, the methods further comprise extracting the PCH formed after the hydrolysis step from the aqueous medium using the DCP as an extraction solvent. In some embodiments, where the DCP is used as an extraction solvent for the PCH, the DCP may be separated from the PCH and the separated DCP may be recirculated to the separation reaction/reactor and/or to the hydrolysis reaction/reactor.

In some embodiments of the foregoing aspect and embodiments, the one or more products further comprise isopropanol and/or isopropyl chloride. In some embodiments of the foregoing aspect and embodiments, the method further comprises converting the isopropanol and/or the isopropyl chloride back to the propylene, DCP, and/or PCH. In some embodiments, other isopropanol and/or other isopropyl chloride (waste streams from other processes or sources) may be used in this process and are converted to more valuable propylene, DCP, and/or PCH.

The selectivity and the STY of the PCH formed by the methods and systems provided herein, have been described earlier.

Reaction Conditions for the Hydrolysis of the DCP to the PCH

In the above noted aspects, a recirculating stream of the DCP hydrolyzes to the PCH in the hydrolysis reactor by addition of reactants and removal of products. Some reaction conditions such as, but not limited to, low temperature and longer residence time have been described above. In some embodiments, the hydrolysis reactor runs at different pressure and temperature conditions than the chlorination reactor and that drives the hydrolysis reaction. For example, in some embodiments, since there is no propylene in the hydrolysis reactor, it can be run at a lower pressure and/or longer residence time than the chlorination reactor, thereby expediting the hydrolysis reaction. In some embodiments, the temperature of the hydrolysis reaction/reactor is between 20° C.−200° C. or between 90° C.−160° C. In some embodiments, the residence time in the hydrolysis reaction/reactor is less than two hrs; or less than one hr; or between 1 sec-2 hrs; or between 1 min-1 hr. In some embodiments, the hydrolysis of the DCP to the PCH in the hydrolysis reactor may be catalyzed by the presence of a heterogenous catalyst, such as, but not limited to, a noble metal. The noble metals have been described herein for the formation of the PCH and can be used in the hydrolysis of the DCP to the PCH as well.

In some embodiments of the aforementioned aspects, both the DCP and the water may be minimally soluble in one another and as a result the hydrolysis reactor may contain one or two liquid phases. If the reactor contains both liquid phases, the reaction can proceed in both phases, i.e. both the DCP which is soluble in the water-rich phase and the water which is soluble in the DCP-rich phase, may react. In the hydrolysis reactor, a single liquid phase or both the DCP rich phase (with dissolved water) and the water rich phase (with dissolved DCP) are contemplated.

In some embodiments, the hydrolysis of the DCP to the PCH comprises concentration of the metal chloride with metal ion in the higher oxidation state (for example only CuCl₂) of between about 1-3M.

In some embodiments of the above noted aspects, when the metal chloride is copper chloride (CuCl as the metal chloride with metal ions in the lower oxidation state and CuCl₂ as the metal chloride with metal ions in the higher oxidation state), the hydrolysis of the DCP to the PCH may be carried out in presence of copper hydroxychloride species of stoichiometry Cu_(x)Cl_(y)(OH)_((2x-y)). The formation of the copper hydroxychloride species of stoichiometry Cu_(x)Cl_(y)(OH)_((2x-y)) via the oxychlorination reaction has been described above. In some embodiments, the copper hydroxychloride species of stoichiometry Cu_(x)Cl_(y)(OH)_((2x-y)), such as, e.g. Cu(OH)Cl, can serve as a base consuming HCl via:

Cu(OH)Cl+HCl→CuCl₂+H₂O  (XI)

In some embodiments, the Cu(OH)Cl may serve as an active site to form the PCH directly from the DCP as shown in reaction (XII) below:

Cu(OH)Cl+ClCH₂CH(Cl)CH₃→ClCH₂CH(OH)CH₃+CuCl₂  (XII)

Without being limited by any theory, it is contemplated that either or both of the reactions may occur in the presence of copper hydroxychloride species of stoichiometry Cu_(x)Cl_(y)(OH)_((2x-y)), such as, e.g. Cu(OH)Cl.

Forming the PO from the PCH

In some embodiments of the foregoing aspect and embodiments, the methods further comprise reacting the PCH with a base to form the PO. Various process configurations that lead to the epoxidation step have been described above and are illustrated in the figures herein.

Typically, the conversion of the PCH to the PO is a ring-closing reaction whereby the chlorohydrin molecule may be combined in a near stoichiometric ratio with a base such as e.g. sodium hydroxide (NaOH) or lime (CaO). The products are PO, the chloride salt of the base (e.g. NaCl or CaCl₂ respectively) and water. Because the PO may be a reactive molecule, it may need to be removed from the reaction media quickly. Typically, the short residence time requirement may be achieved by steam stripping the PO as it is formed in the reactor. However, because the PCH feeding the reactor may be diluted with a large excess of water due to upstream reaction selectivity considerations (described further herein below), the steam demand for PO stripping may be very high.

In some aspects noted above, there are provided methods and systems comprising reacting the PCH with a base to form PO in presence of DCP or the methods and systems comprise reacting the solution of the PCH and the DCP with a base to form PO. In these aspects, the DCP is not separated from the PCH after hydrolysis and the solution is directly subjected to epoxidation. In such embodiments, the separation of the DCP and the PCH step (before and/or after hydrolysis step) may be combined with the epoxidation step such that when the base is added into the epoxidation reactor, the base reacts with the PCH to form the PO, which may leave the reactor as a vapor. In this process, some DCP may be converted to the PCH which would also form the PO. In some embodiments, the residual levels of un-reacted PCH may leave the reactor in the DCP extraction solvent (DCP as an extraction solvent has been described before) and return to the process where appropriate.

The methods and systems provided herein for converting the PCH to the PO in the presence of the DCP (where the mol % of the DCP may be equal to or greater than the mol % of the PCH) has a number of advantages. First, it may obviate the need for separation of the PCH from the DCP prior to the epoxidation. To maintain high selectivity of the PCH during the hydrolysis reaction, the DCP level may be in excess relative to the converted amount of the DCP as described above. The PCH may be separated from the DCP via a typical separation operation. If PCH were the lighter (lower boiling) component, distillation would be an option. However, because PCH is the heavier component, separation by distillation may require the excess DCP be removed in the overhead of the column which in turn may lead to prohibitive steam demand. Alternative separation technologies, such as absorption or selective permeation, may be equally prohibitive due to either capital equipment costs or operating costs. Second, because the PO may also be soluble in the DCP, the reactor may not require steam stripping inside the reactor. The PO can be removed from the reactor in the DCP phase if desired and separated downstream. Third, additional side reactions may be minimized because PO may react much more slowly in the organic (DCP) phase. Finally, the total waste water demand may be significantly reduced because the water leaving the reactor would primarily be that which came in with the caustic (and low levels of soluble water with the organic phase). In some embodiments, when using NaOH as the base for the PO formation, the resulting aqueous solution may be concentrated enough in NaCl to merit removing the waste organics and using the brine back in the electrochemical cell.

In addition to the advantages described above, the conversion of the PCH to the PO in the presence of DCP may also allow for process options that minimize by-product losses, such as, a single aqueous phase reactor that contains both reactants and products; minimizing by-product formation by running the reactor with a short residence time; step-wise addition of the NaOH; and recycling of the product stream back to the reactor. The step-wise addition of NaOH (e.g. along a length of pipe if the reaction is done in a continuous system) may reduce the by-product formation because the aqueous salt solutions resulting from the early additions may dilute the later additions. In this way, the caustic concentrations within the aqueous phase can be more easily managed along the reactor length. The recycling of the aqueous product stream back to the reactor inlet may also minimize the NaOH concentration in the aqueous phase. The recycling option has other advantages too. For example, the recycle stream may return salt-rich brine to the reactor. The presence of the salt may minimize the solubility of the PO in the aqueous phase which may improve reactor selectivity. Further, the highly concentrated salt may be advantageous because the resulting brine stream exiting the epoxidation unit may serve as a feedstock for electrolysis cells after removal of the residual, soluble organics. Furthermore, the recycle of reactor outlet may allow the reactor to run in such a way as to produce a high salt concentration outlet stream without having to feed a high concentration NaOH stream directly to the reactor. The other advantages of the high salt concentration outlet stream have also been described further herein.

In some embodiments of the foregoing aspect and embodiments, the base is an alkali metal hydroxide, such as e.g. NaOH or alkali metal oxide; alkaline earth metal hydroxide or oxide, such as e.g. Ca(OH)₂ or CaO; or metal hydroxide chloride (for example only, M_(x) ^(n+)Cl_(y)(OH)_((nx-y))). In some embodiments of the foregoing aspect and embodiments, metal in the metal hydroxychloride is same as metal in the metal chloride. In some embodiments of the foregoing aspect and embodiments, the method further comprises forming the metal hydroxychloride by oxychlorinating the metal chloride with the metal ion in the lower oxidation state to the higher oxidation state in presence of water and oxygen (as explained above).

Typically, in chlorohydrin processes for the production of propylene oxide, the NaOH may be combined and reacted with an approximately 4-5 wt % solution of propylene chlorohydrins. The propylene chlorohydrins are a mix of 1-chloro-2-propanol (approximately 85-90%) and 2-chloro-1-propanol (approximately 10-15%). The propylene oxide formation reaction is shown as below:

C₃H₆(OH)Cl+NaOH→C₃H₆O(PO)+NaCl+H₂O  (XIII)

Propylene oxide may be rapidly stripped from the solution in either a vacuum stripper or steam stripper. A primary disadvantage of the process may be the generation of a dilute NaCl brine stream with about 3-6 wt % NaCl with flow rate exceeding 40-45 tonnes of brine per tonne of propylene oxide. The large amount of dilute brine may result in large amount of waste water. The reason for the large volume of water may be that the reactor producing the propylene chlorohydrins must operate at dilute concentrations of about 4-5 wt % propylene chlorohydrin in order to achieve high selectivity.

Applicants have discovered that using the methods of the invention that produce PCH in high selectivity and high STY, the amount of dilute brine generated after the PO formation can be substantially reduced. In some embodiments of the foregoing aspect and embodiments, the reaction forms between about 5-40 tonnes of brine per tonne of PO which is substantially less brine compared to the brine generated in a typical PO reaction.

In one aspect, there is provided a method to form propylene oxide (PO), comprising chlorinating propylene in an aqueous medium comprising metal chloride with metal ion in higher oxidation state and salt to result in one or more products comprising between about 5-99.9 wt % PCH, and the metal chloride with the metal ion in lower oxidation state; and reacting the PCH with a base to form PO and brine in water, wherein the reaction forms between about 5-42 tonnes of brine per tonne of PO.

In one aspect, there is provided a method to form propylene oxide (PO), comprising chlorinating propylene in an aqueous medium comprising metal chloride with metal ion in higher oxidation state and salt to result in one or more products comprising DCP and PCH, and the metal chloride with the metal ion in lower oxidation state; extracting the DCP and the PCH with re-circulating DCP from the same process and/or the other DCP; hydrolyzing the DCP in the mixture of the DCP and the PCH to the PCH; and reacting the PCH in presence of remaining DCP with a base to form PO and brine in water. In some embodiments of the foregoing aspect, the reaction forms between about 5-42 or about 5-40 tonnes of brine per tonne of PO. In some embodiments of the foregoing aspect, the selectivity of the PCH formed (after chlorination and hydrolysis) is between about 10-99.9 wt %. In some embodiments of the foregoing aspect and embodiments, the base is between about 5-35 wt % or between about 8-15 wt %. The bases have been described herein and include without limitation, the alkali metal hydroxide e.g. sodium hydroxide or potassium hydroxide; alkaline earth metal hydroxide e.g. calcium hydroxide or oxide e.g. CaO or MgO; or metal hydroxide chloride. The PO formation has been illustrated in FIGS. 1-5.

In some embodiments of the aforementioned aspects, the PO formed is between about 5-50 wt %; or between about 5-40 wt %; or between about 5-30 wt %; or between about 5-20 wt %; or between about 5-10 wt %; or between about 10-50 wt %; or between about 10-40 wt %; or between about 10-30 wt %; or between about 10-20 wt %; or between about 20-50 wt %; or between about 20-40 wt %; or between about 20-30 wt %; or between about 30-50 wt %; or between about 30-40 wt %; or between about 40-50 wt %. In some embodiments of the aspects and embodiments provided herein, the PO formed is between about 1-25 wt %; or between about 2-20 wt %; or between about 3-15 wt %.

In some embodiments of the aspect and embodiments provided herein, the reaction forms between about 5-42 tonnes of brine per tonne of PO; or between about 5-40 tonnes of brine per tonne of PO; or between about 5-35 tonnes of brine per tonne of PO; or between about 5-30 tonnes of brine per tonne of PO; or between about 5-25 tonnes of brine per tonne of PO; or between about 5-20 tonnes of brine per tonne of PO; or between about 5-10 tonnes of brine per tonne of PO. In some embodiments of the aspect and embodiments provided herein, the reaction forms between about 3-40 tonnes of brine per tonne of PO; or between about 4-20 tonnes of brine per tonne of PO; or between about 4-12 tonnes of brine per tonne of PO.

In some embodiments of the aspect and embodiments provided herein, the base is between about 5-50 wt %; or between about 5-40 wt %; or between about 5-30 wt %; or between about 5-20 wt %; or between about 5-10 wt %; or between about 10-50 wt %; or between about 10-40 wt %; or between about 10-30 wt %; or between about 10-20 wt %; or between about 20-50 wt %; or between about 20-40 wt %; or between about 20-30 wt %; or between about 30-50 wt %; or between about 30-40 wt %; or between about 40-50 wt %; or between about 8-15 wt %; or between about 10-15 wt %; or between about 12-15 wt %; or between about 14-15 wt %; or between about 8-10 wt %; or between about 8-12 wt %. In some embodiments of the aspect and embodiments provided herein, the base is between about 5-38 wt %; or between about 7-33 wt %; or between about 8-20 wt %.

In some embodiments of the foregoing aspects and embodiment, the method further comprises transferring aqueous medium comprising the metal chloride with the metal ion in the lower oxidation state and the salt to an anode electrolyte in contact with an anode in an electrochemical cell and oxidizing the metal ion from the lower oxidation state to the higher oxidation state at the anode.

In some embodiments of the foregoing aspects and embodiment, the method further comprises transferring the aqueous medium comprising the metal chloride with the metal ion in the lower oxidation state and the salt to an oxychlorination reaction and oxidizing the metal ion from the lower oxidation state to the higher oxidation state in the presence of the oxidant.

In some embodiments of the foregoing aspect and embodiments, the one or more products further comprise hydrochloric acid (HCl). In some embodiments of the foregoing aspect and embodiments, the method further comprises after the chlorinating step, oxychlorinating the metal chloride with the metal ion in the lower oxidation state to the metal ion in the higher oxidation state in presence of the HCl and oxygen, or hydrogen peroxide.

In some embodiments of the foregoing aspect and embodiments, the method further comprises recirculating the metal chloride in the higher oxidation state back to the chlorinating step.

In the methods and systems provided herein, the separation and/or purification may include one or more of the separation and purification of the organic products from the metal ion solution and/or the separation and purification of the organic products from each other, to improve the overall yield of the PCH, improve selectivity of the PCH, improve purity of the PCH, improve efficiency of the systems, improve ease of use of the solutions in the overall process, improve reuse of the metal solution, and/or to improve the overall economics of the process.

In some embodiments, the solution containing the one or more products and the metal chloride may be subjected to a washing step which may include rinsing with an organic solvent or passing the organic product through a column to remove the metal ions. In some embodiments, the organic products may be purified by distillation.

In one aspect, there are provided systems, comprising reactors configured to carry out the reactions of the preceding aspects and embodiments.

The systems provided herein include one or more reactors that carry out the chlorination reaction; the hydrolysis reaction; the oxychlorination reaction; and the epoxidation reaction. The “reactor” as used herein is any vessel or unit in which the reaction provided herein is carried out. For example, the chlorination reactor is configured to contact the metal chloride solution with the propylene to form the one or more products comprising DCP and/or PCH. The reactor may be any means for contacting the metal chloride with the propylene. Such means or such reactor are well known in the art and include, but not limited to, pipe, column, duct, tank, series of tanks, container, tower, conduit, and the like. The reactor may be equipped with one or more of controllers to control temperature sensor, pressure sensor, control mechanisms, inert gas injector, etc. to monitor, control, and/or facilitate the reaction.

In some embodiments, the reactor system may be a series of reactors connected to each other. For example, to increase the yield of the PCH, the chlorination mixture may be kept either in the same reaction vessel (or reactor), or in a second reaction vessel (hydrolysis reactor) that does not contain additional propylene. Since the PCH and/or the DCP solubility may be limited in the aqueous medium, a second reaction vessel may be a stirred tank. The stirring may increase the mass transfer rate of the PCH and/or the DCP into the aqueous medium accelerating the reaction to the PCH.

The reactor configuration includes, but is not limited to, design parameters of the reactor such as, e.g. length/diameter ratio, flow rates of the liquid(s) and gas(es), material of construction, packing material and type of reactor such as, packed column, bubble column, or trickle-bed reactor, or combinations thereof. In some embodiments, the systems may include one reactor or a series of multiple reactors connected to each other or operating separately. The reactor may be a packed bed such as, but not limited to, a hollow tube, pipe, column or other vessel filled with packing material. The reactor may be a spray reactor. The reactor may be a trickle-bed reactor. The reactor may be a bubble column. In some embodiments, the packed bed reactor includes a reactor configured such that the aqueous medium containing the metal ions and the propylene flow counter-currently in the reactor or includes the reactor where the aqueous medium containing the metal ions flows in from the top of the reactor and the propylene gas is pressured in from the bottom. In some embodiments, in the latter case, the propylene may be fed in such a way that only when the propylene gets consumed, that more propylene flows into the reactor. The trickle-bed reactor includes a reactor where the aqueous medium containing the metal ions and the propylene flow co-currently in the reactor.

In some embodiments, the reactor may be configured for both the reaction and separation of the products. The processes and systems described herein may be batch processes or systems or continuous flow processes or systems.

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as their invention nor are they intended to represent that the experiments below are all or the only experiments performed. Various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description and accompanying figures. Such modifications fall within the scope of the appended claims. Efforts have been made to ensure accuracy with respect to numbers used (e.g. amounts, temperature, etc.) but some experimental errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, molecular weight is weight average molecular weight, temperature is in degrees Centigrade, and pressure is at or near atmospheric.

In the examples and elsewhere, abbreviations have the following meanings:

g = gram M = molar mmol = millimole mol = mole mol/kg = mole/kilogram μl = microliter ml = milliliter N = normal psi = pounds per square inch psig = pounds per square inch guage Pt = platinum rpm = revolutions per minute STY = space time yield umol = micromole

EXAMPLES Example 1 Formation of PCH, DCP, Isopropanol and Isopropyl Chloride from Propylene Using Copper Chloride Experiment 1

A solution of CuCl₂ (1.0 mol/kg), CuCl (0.19 mol/kg), NaCl (0.66 mol/kg), and HCl (0.0091 mol/kg) was heated in a Parr reactor under propylene pressure to 130° C. for 15 minutes. The reactor was depressurized into a bubbler trap at 0° C. to capture volatile compounds. When the reactor was opened, the solution was extracted three times with an organic solvent, e.g. ethyl acetate or dichloromethane, which was analyzed with a gas chromatograph equipped with a mass spectrometer. A total of 11.4 umol DCP and 12.0 umol PCH were measured. The amounts of recyclable products measured were 622 umol isopropanol, 47.9 umol acetone, and 73.0 umol isopropyl chloride.

Experiment 2

A solution of CuCl₂ (0.71 mol/kg), CuCl (0.71 mol/kg), and NaCl (2.76 mol/kg) was heated in a Parr reactor under propylene pressure to 150° C. for 15 minutes. The reactor was depressurized into a bubbler trap at 0° C. to capture volatile compounds. When the reactor was opened, the solution was extracted three times with an organic solvent, e.g. ethyl acetate or dichloromethane, which was analyzed with a gas chromatograph equipped with a mass spectrometer. A total of 15.6 umol DCP and 62.4 umol PCH were measured. The amounts of recyclable products measured were 1087 umol isopropanol, 18.8 umol acetone, and 80.1 umol isopropyl chloride.

Example 2 Formation of PCH from Propylene Using Palladium Chloride and Copper Chloride

A solution of CuCl₂ (2.80 mol/kg), CuCl (0.54 mol/kg), NaCl (1.84 mol/kg), and PdCl₂ (0.012 mol/kg) are heated in a Parr reactor under propylene pressure to 130° C. for 15 minutes. The reactor was depressurized into a bubbler trap at 0° C. to capture volatile compounds. When the reactor was opened, the solution was extracted three times with an organic solvent, e.g. ethyl acetate or dichloromethane, which was analyzed with a gas chromatograph equipped with a mass spectrometer. A total of 0.29 mmol DCP and 1.24 mmol PCH were measured. The amounts of recyclable products measured were 9.23 mmol isopropanol, 3.17 mmol acetone, and 10.9 mmol isopropyl chloride.

Example 3 Recycling of Isopropanol

A solution of CuCl₂ (3.0 mol/kg), CuCl (0.50 mol/kg), and NaCl (2.0 mol/kg) were heated with added isopropanol in a Parr reactor at 140° C. for 15 minutes. The reactor was constantly purged with a flow of N₂ into a bubbler trap at 0° C. to capture volatile compounds. When the reactor was opened, the solution was extracted three times with an organic solvent, e.g. ethyl acetate or dichloromethane, which was analyzed with a gas chromatograph equipped with a mass spectrometer. Propylene, isopropanol, isopropyl chloride, PCH, and DCP were all detected, indicating that isopropanol can be recycled and converted into desired products.

Example 4 Recycling of Isopropyl Chloride

Similar to Example 3, reaction was conducted with isopropyl chloride instead of isopropanol. The same products were observed.

Example 5 Conversion of DCP to PCH

In order to measure conversion of DCP to PCH, seven aqueous salt solutions were tested. The salt solutions comprised CuCl₂, CuCl, and NaCl. The salts were weighed into 10 ml vials with water added to bring the solution volume to approximately 4 ml. 50 μL of DCP was added to each vial and then a stir bar was also added. The vials were closed with a split-septa cap and placed inside an 8 well high throughput reactor. The entire system was heated to 150° C. for 30 minutes, during which time the vials were all stirred at 600 rpm. The organics were extracted using 4 ml of ethyl acetate and the resulting solutions were measured by GC-MS. Using the peak areas from the GC-MS, the following conversions were obtained shown in Table

TABLE I Experiment 1 2 3 4 5 6 7 CuCl₂ 3.0 3.0 1.5 3.0 3.0 0.0 0.0 (mol/kg) CuCl 1.0 1.0 0.5 0.0 0.0 1.0 1.0 (mol/kg) NaCl 2.0 0.0 1.0 2.0 0.0 2.0 0.0 (mol/kg) Estimated 7.0% 12.7% 10.1% 7.2% 10.7% 14.7% 13.6% Conver- sion To PCH

It may be noted that some DCP partitions into the vapor space in the vials, therefore, these numbers represent a lower bound on the conversion to PCH. It was observed that lower CuCl₂ concentrations lead to higher conversion to PCH.

Example 6 Improved Selectivity for PCH Over DCP Experiment 1

An aqueous solution of CuCl₂ (2.0 mol/kg) and CuCl (1.0 mol/kg) was heated in a Parr reactor under propylene pressure to 140° C. for 30 minutes. The reactor was depressurized into a bubbler trap at 0° C. to capture volatile compounds. When the reactor was opened, the solution was extracted three times with an organic solvent, e.g. ethyl acetate or dichloromethane, which was analyzed with a gas chromatograph equipped with a mass spectrometer. A total of 47 umol DCP and 229 umol PCH were measured. The amounts of recyclable products measured were 5834 umol isopropanol, 23 umol acetone, and 189 umol isopropyl chloride.

Experiment 2

An aqueous solution of CuCl₂ (1.0 mol/kg), CuCl (1.0 mol/kg), and NaCl (1.0 mol/kg) was heated in a Parr reactor under propylene pressure to 140° C. for 30 minutes. The reactor was depressurized into a bubbler trap at 0° C. to capture volatile compounds. When the reactor was opened, the solution was extracted three times with an organic solvent, e.g. ethyl acetate or dichloromethane, which was analyzed with a gas chromatograph equipped with a mass spectrometer. A total of 15 umol DCP and 88 umol PCH were measured. The amounts of recyclable products measured were 917 umol isopropanol, 4 umol acetone, and 35 umol isopropyl chloride.

Example 7 Lowering of Water in PO Process

A 40 wt % solution of propylene chlorohydrin is combined with a 10 wt % solution of sodium hydroxide and brine. The use of the more concentrated PCH reduces the brine effluent from 46.2 to 10.1 tonnes per tonne of propylene oxide resulting in significant cost savings for the handling of this stream. In another example, feeding a solution of PCH in DCP may lower the total water discharged to around 7 tonnes per tonne PO, which is due to the amount of water contained in the added NaOH solution.

Example 8 Formation of PO from PCH

A glass vial was loaded with 5 mL of 0.1 N NaOH and 100 ul of PCH (70% 1-chloro-2-propanol and 30% 2-chloro-1-propanol). The vial was stirred with a magnetic stir bar for 20 hours. Afterward, a 1 ml aliquot was extracted with 2 ml of ethyl acetate that was subsequently analyzed by gas chromatography with a mass spectrometer detector. Propylene oxide as well as both isomers of PCH was observed, as determined by their fragmentation patterns.

Example 9 Formation of PO from PCH in Presence of DCP

A 500 ml round bottom flask was charged with 99.90 g DCP, 0.933 g octane as an internal standard, and 4.764 g (50.4 mmol) PCH. The flask was equipped with a condenser on top of which was a barbed fitting with a tube that ran into a vial of ethyl acetate in ice water bath. Any gas generated and distilled through the condenser was collected in the ethyl acetate trap. The solution was brought to a boil at roughly 90° C. At specific time intervals, 4 charges each of 10 ml of 1 N NaOH (10 mmol) was added through the top of the condenser and allowed to trickle down into the hot solution. At the end of the reaction, 34.5 mmol propylene oxide and 3.0 mmol propylene glycol were measured as products, and 7.9 mmol PCH was measured as un-reacted. This correlates to 92% propylene oxide with 90% mass balance closure.

Example 10 Formation of PO from PCH in Presence of DCP

A glass vial was charged with 1900 ul DCP and 100 ul (1.2 mmol) PCH and held at room temperature. To this, 300 ul 1 N NaOH (0.3 mmol) was added and the vial was mixed vigorously. Samples from before and after the reaction showed a reduction of the PCH amount by 31% with a concomitant increase in propylene oxide. 

What is claimed is:
 1. A method to form propylene chlorohydrin (PCH), comprising: (i) contacting an anode with an anode electrolyte in an electrochemical cell wherein the anode electrolyte comprises metal chloride and saltwater; contacting a cathode with a cathode electrolyte in the electrochemical cell; applying voltage to the anode and the cathode and oxidizing the metal chloride with metal ion in a lower oxidation state to a higher oxidation state at the anode; (ii) withdrawing the anode electrolyte from the electrochemical cell and chlorinating propylene with the anode electrolyte comprising metal chloride with metal ion in higher oxidation state and the saltwater to result in one or more products comprising PCH and 1,2-dichloropropane (DCP), and the metal chloride with the metal ion in lower oxidation state; (iii) extracting the one or more products comprising PCH and DCP from aqueous medium by extracting with DCP as an extraction solvent; and (iv) hydrolyzing the DCP with water to form the PCH.
 2. The method of claim 1, wherein the DCP as the extraction solvent is the DCP separated and recirculated from the same process and/or is DCP from other sources.
 3. The method of claim 1, wherein amount of the DCP in the hydrolysis is between about 10-95% by volume.
 4. The method of claim 1, further comprising after extraction, transferring aqueous medium comprising the metal chloride with metal ions in the higher oxidation state and the lower oxidation state to the oxychlorination reaction and oxidizing the metal ion of the metal chloride from the lower oxidation state to the higher oxidation state in presence of an oxidant.
 5. The method of claim 4, wherein the oxidant is X₂ gas alone; or HX gas and/or HX solution in combination with gas comprising oxygen or ozone; or hydrogen peroxide; or HXO or salt thereof; or HXO₃ or salt thereof; or HXO₄ or salt thereof; or combinations thereof, wherein each X independently is a halogen selected from fluorine, chlorine, iodine, and bromine.
 6. The method of claim 5, further comprising forming HCl by the hydrolysis of the DCP to the PCH; separating the HCl; and transferring the HCl to the oxychlorination reaction; and/or adding other HCl to the oxychlorination reaction.
 7. The method of claim 4, further comprising recirculating the metal chloride with the metal ion in the higher oxidation state back to the chlorination reaction and/or to the electrochemical cell.
 8. The method of claim 1, wherein the PCH is formed with selectivity of between about 20-100% by wt and/or more than 0.01 STY.
 9. The method of claim 1, further comprising after hydrolysis, transferring organic medium comprising PCH and DCP to epoxidation; and epoxidizing the PCH with a base to form PO in presence of the DCP.
 10. The method of claim 9, wherein the base is selected from alkali metal hydroxide, alkali metal oxide, alkaline earth metal hydroxide, alkaline earth metal oxide, or metal hydroxychloride species of stoichiometry M_(x) ^(n+)Cl_(y)(OH)_((nx-y)).
 11. The method of claim 10, wherein the base is between about 5-38 wt %.
 12. The method of claim 9, wherein the reaction forms between about 5-40 tonnes of brine per tonne of PO.
 13. The method of claim 1, wherein the saltwater comprises alkali metal chloride or alkaline earth metal chloride.
 14. The method of claim 1, wherein metal ion in the metal chloride is selected from the group consisting of iron, chromium, copper, tin, silver, cobalt, uranium, lead, mercury, vanadium, bismuth, titanium, ruthenium, osmium, europium, zinc, cadmium, gold, nickel, palladium, platinum, rhodium, iridium, manganese, technetium, rhenium, molybdenum, tungsten, niobium, tantalum, zirconium, hafnium, and combination thereof.
 15. The method of claim 1, wherein the metal chloride is copper chloride.
 16. The method of claim 9, further comprising adding other DCP to the chlorination; to the hydrolysis; and/or to the epoxidation for the extraction.
 17. The method of claim 16, wherein the other DCP is obtained from a traditional chlorohydrin process and/or from direct chlorination of propylene with chlorine.
 18. A system to form PO, comprising: (i) an electrochemical cell comprising an anode chamber comprising an anode and an anode electrolyte wherein the anode electrolyte comprises metal chloride and saltwater and the anode is configured to oxidize the metal chloride with metal ion in a lower oxidation state to a higher oxidation state; a cathode chamber comprising a cathode and a cathode electrolyte; and a voltage source configured to apply voltage to the anode and the cathode; (ii) a chlorination reactor operably connected to the anode chamber of the electrochemical cell and configured to obtain the anode electrolyte and chlorinate propylene with the anode electrolyte comprising the metal chloride with the metal ion in the higher oxidation state in the saltwater to result in one or more products comprising DCP and the metal chloride with the metal ion in the lower oxidation state; (iii) a hydrolysis reactor operably connected to the chlorination reactor and configured to obtain the one or more products comprising DCP from the chlorination reactor with or without the saltwater comprising metal chloride and configured to hydrolyze the DCP to PCH; and (iv) an epoxidation reactor operably connected to the hydrolysis reactor and configured to obtain the solution comprising DCP and PCH and epoxidize the PCH to PO in presence of a base.
 19. The system of claim 18, further comprising an oxychlorination reactor operably connected to the chlorination reactor and/or the electrochemical cell; operably connected to the hydrolysis reactor; and configured to obtain aqueous medium from the chlorination reactor and/or the electrochemical cell comprising the metal chloride with metal ion in the lower oxidation state and the higher oxidation state; configured to obtain HCl produced in the hydrolysis reactor; and configured to oxidize the metal chloride with metal ion in the lower oxidation state to the higher oxidation state using an oxidant comprising the HCl and oxygen, or hydrogen peroxide.
 20. The system of claim 18, further comprising the chlorination reactor and/or the hydrolysis reactor operably connected to a traditional chlorohydrin system and/or to another chlorination reactor chlorinating propylene with chlorine, and configured to obtain other DCP from the traditional chlorohydrin system and/or from the another chlorination reactor chlorinating propylene with chlorine. 